1. Field of the Invention
This invention relates to a means to weld the static side of a belleville seal to a leg of a three cone rock bit.
More particularly, this invention provides a means to hold one leg of a three cone rock bit in a rotary type fixture to weld the static portion of a belleville seal to an intersection formed between the journal bearing extending from the leg and the leg backface. The welding fixture rotates through 360.degree. while, for example, a fixed laser welder directs a narrow beam at the intersection.
2. Description of the Prior Art
U.S. Pat. No. 3,680,873, assigned to the same assignee as the present invention, describes a belleville seal that includes an inner annular ring, preferably metallic, and an outer annular element of yieldable seal material. The inner resilient ring has a weakened breakpoint which will remain unbroken during the bonding of the annular yieldable rubberlike material to the ring. The ring is separable at the breakpoint when forced over an abutment on one of the relatively rotatable parts. The ring and yieldable material are returned or "spring back" to approximately their original diameters after passing the ridged abutment. The patent addresses the problem of securing the inner diameter static portion of the belleville seal against a rock bit leg backface to prevent the static portion or inner annular portion of the belleville seal from rotating. The present practice is to spot weld the inner metallic ring of the belleville seal to secure the broken ends of the ring and to prevent rotation of the ring during operation of the rock bit.
The recently filed patent application, Ser. No. 628,068, describes an advance in the state of the art in that the entire ring is welded through 360.degree. at the interface between the journal and the leg backface, thus obviating any chance of a leak through this juncture between the belleville spring and the journal.
The related application is incorporated by reference and teaches a means to hermetically seal a belleville seal to a journal of a rock bit. Heretofore, no one has hermetically sealed the static side of a belleville seal after it has been placed at an intersection between the journal and the leg backface immediately adjacent the seal.
The present invention teaches the means in which the 360.degree. weld operation is performed by preferably a continuouswave laser welding process. More particularly, it describes the means in which each leg is rigidly mounted to the welding fixture so that an accurate 360.degree. weld operation may proceed, thus assuring continuity and good quality control during the operation. Other types of welders may be used in cooperation with the welding fixture, such as an electron beam or a pulsed laser welding process, to accomplish the circumferential weld.